A042499 - OEIS

%I #15 Mar 19 2017 10:54:52

%S 1,1,7,8,439,447,3121,3568,195793,199361,1391959,1591320,87323239,

%T 88914559,620810593,709725152,38945968801,39655693953,276880132519,

%U 316535826472,17369814762007,17686350588479

%N Denominators of continued fraction convergents to sqrt(777).

%H Vincenzo Librandi, <a href="/A042499/b042499.txt">Table of n, a(n) for n = 0..200</a>

%H <a href="/index/Rec#order_08">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 0, 446, 0, 0, 0, -1).

%F a(n) = 446*a(n-4)-a(n-8). G.f.: -(x^2-x-1)*(x^4+8*x^2+1)/(x^8-446*x^4+1). [_Colin Barker_, Jul 16 2012]

%t Denominator[Convergents[Sqrt[777], 30]] (* _Vincenzo Librandi_, Oct 25 2013 *)

%Y Cf. A042498.

%K nonn,cofr,frac,easy

%O 0,3

%A _N. J. A. Sloane_.